39.E: The Respiratory System (Exercises)
39.1: Systems of Gas Exchange
Review Questions
The respiratory system ________.
- provides body tissues with oxygen
- provides body tissues with oxygen and carbon dioxide
- establishes how many breaths are taken per minute
- provides the body with carbon dioxide
- Answer
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A
Air is warmed and humidified in the nasal passages. This helps to ________.
- ward off infection
- decrease sensitivity during breathing
- prevent damage to the lungs
- all of the above
- Answer
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C
Which is the order of airflow during inhalation?
- nasal cavity, trachea, larynx, bronchi, bronchioles, alveoli
- nasal cavity, larynx, trachea, bronchi, bronchioles, alveoli
- nasal cavity, larynx, trachea, bronchioles, bronchi, alveoli
- nasal cavity, trachea, larynx, bronchi, bronchioles, alveoli
- Answer
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B
Free Response
Describe the function of these terms and describe where they are located: main bronchus, trachea, alveoli, and acinus.
- Answer
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The main bronchus is the conduit in the lung that funnels air to the airways where gas exchange occurs. The main bronchus attaches the lungs to the very end of the trachea where it bifurcates. The trachea is the cartilaginous structure that extends from the pharynx to the primary bronchi. It serves to funnel air to the lungs. The alveoli are the sites of gas exchange; they are located at the terminal regions of the lung and are attached to the respiratory bronchioles. The acinus is the structure in the lung where gas exchange occurs.
How does the structure of alveoli maximize gas exchange?
- Answer
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The sac-like structure of the alveoli increases their surface area. In addition, the alveoli are made of thin-walled parenchymal cells. These features allow gases to easily diffuse across the cells.
39.2: Gas Exchange across Respiratory Surfaces
Review Questions
The inspiratory reserve volume measures the ________.
- amount of air remaining in the lung after a maximal exhalation
- amount of air that the lung holds
- amount of air the can be further exhaled after a normal breath
- amount of air that can be further inhaled after a normal breath
- Answer
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D
Of the following, which does not explain why the partial pressure of oxygen is lower in the lung than in the external air?
- Air in the lung is humidified; therefore, water vapor pressure alters the pressure.
- Carbon dioxide mixes with oxygen.
- Oxygen is moved into the blood and is headed to the tissues.
- Lungs exert a pressure on the air to reduce the oxygen pressure.
- Answer
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D
The total lung capacity is calculated using which of the following formulas?
- residual volume + tidal volume + inspiratory reserve volume
- residual volume + expiratory reserve volume + inspiratory reserve volume
- expiratory reserve volume + tidal volume + inspiratory reserve volume
- residual volume + expiratory reserve volume + tidal volume + inspiratory reserve volume
- Answer
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D
Free Response
What does FEV1/FVC measure? What factors may affect FEV1/FVC?
- Answer
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FEV1/FVC measures the forced expiratory volume in one second in relation to the total forced vital capacity (the total amount of air that is exhaled from the lung from a maximal inhalation). This ratio changes with alterations in lung function that arise from diseases such as fibrosis, asthma, and COPD.
What is the reason for having residual volume in the lung?
- Answer
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If all the air in the lung were exhaled, then opening the alveoli for the next inspiration would be very difficult. This is because the tissues would stick together.
How can a decrease in the percent of oxygen in the air affect the movement of oxygen in the body?
- Answer
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Oxygen moves from the lung to the bloodstream to the tissues according to the pressure gradient. This is measured as the partial pressure of oxygen. If the amount of oxygen drops in the inspired air, there would be reduced partial pressure. This would decrease the driving force that moves the oxygen into the blood and into the tissues. \(\text{P}_{\text{O}_2}\) is also reduced at high elevations: \(\text{P}_{\text{O}_2}\) at high elevations is lower than at sea level because the total atmospheric pressure is less than atmospheric pressure at sea level.
If a patient has increased resistance in his or her lungs, how can this detected by a doctor? What does this mean?
- Answer
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A doctor can detect a restrictive disease using spirometry. By detecting the rate at which air can be expelled from the lung, a diagnosis of fibrosis or another restrictive disease can be made.
39.3: Breathing
Review Questions
How would paralysis of the diaphragm alter inspiration?
- It would prevent contraction of the intercostal muscles.
- It would prevent inhalation because the intrapleural pressure would not change.
- It would decrease the intrapleural pressure and allow more air to enter the lungs.
- It would slow expiration because the lung would not relax.
- Answer
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B
Restrictive airway diseases ________.
- increase the compliance of the lung
- decrease the compliance of the lung
- increase the lung volume
- decrease the work of breathing
- Answer
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B
Alveolar ventilation remains constant when ________.
- the respiratory rate is increased while the volume of air per breath is decreased
- the respiratory rate and the volume of air per breath are increased
- the respiratory rate is decreased while increasing the volume per breath
- both a and c
- Answer
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D
Free Response
How would increased airway resistance affect intrapleural pressure during inhalation?
- Answer
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Increased airway resistance increases the volume and pressure in the lung; therefore, the intrapleural pressure would be less negative and breathing would be more difficult.
Explain how a puncture to the thoracic cavity (from a knife wound, for instance) could alter the ability to inhale.
- Answer
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A puncture to the thoracic cavity would equalize the pressure inside the thoracic cavity to the outside environment. For the lung to function properly, the intrapleural pressure must be negative. This is caused by the contraction of the diaphragm pulling the lungs down and drawing air into the lungs.
When someone is standing, gravity stretches the bottom of the lung down toward the floor to a greater extent than the top of the lung. What implication could this have on the flow of air in the lungs? Where does gas exchange occur in the lungs?
- Answer
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The lung is particularly susceptible to changes in the magnitude and direction of gravitational forces. When someone is standing or sitting upright, the pleural pressure gradient leads to increased ventilation further down in the lung.
39.4: Transport of Gases in Human Bodily Fluids
Review Questions
Which of the following will NOT facilitate the transfer of oxygen to tissues?
- decreased body temperature
- decreased pH of the blood
- increased carbon dioxide
- increased exercise
- Answer
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A
The majority of carbon dioxide in the blood is transported by ________.
- binding to hemoglobin
- dissolution in the blood
- conversion to bicarbonate
- binding to plasma proteins
- Answer
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C
The majority of oxygen in the blood is transported by ________.
- dissolution in the blood
- being carried as bicarbonate ions
- binding to blood plasma
- binding to hemoglobin
- Answer
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D
Free Response
What would happen if no carbonic anhydrase were present in red blood cells?
- Answer
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Without carbonic anhydrase, carbon dioxide would not be hydrolyzed into carbonic acid or bicarbonate. Therefore, very little carbon dioxide (only 15 percent) would be transported in the blood away from the tissues.
How does the administration of 100 percent oxygen save a patient from carbon monoxide poisoning? Why wouldn’t giving carbon dioxide work?
- Answer
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Carbon monoxide has a higher affinity for hemoglobin than oxygen. This means that carbon monoxide will preferentially bind to hemoglobin over oxygen. Administration of 100 percent oxygen is an effective therapy because at that concentration, oxygen will displace the carbon monoxide from the hemoglobin.